Guide to Differential Privacy Modifications: A Taxonomy of Variants and Extensions

Shortly after it was fi
rst introduced in 2006, diff
erential privacy became the fl
agship data privacy defi
nition. Since then, numerous variants and extensions were proposed to adapt it to diff
erent scenarios and attacker models. In this work, we propose a systematic taxonomy of these variants and extensions. We list all data privacy defi
nitions based on diff
erential privacy, and partition them into seven categories, depending on which aspect of the original defi
nition is modifi
ed.
These categories act like dimensions: Variants from the same category cannot be combined, but variants from diff
erent categories can be combined to form new defi
nitions. We also establish a partial ordering of relative strength between these notions by summarizing existing results. Furthermore, we list which of these defi
nitions satisfy some desirable properties, like composition, post-processing, and convexity by either providing a novel proof or collecting existing ones.